Chemical Composition and Structure–Vacancy Disordering in Ag–Au,Cu–Au,Ag–Pd,and Cu–Pd Alloys as Factors of Their Electrocatalytic Activity

The oxalic acid electrooxidation kinetics is studied at polycrystalline electrodes of vacancy-disordered Au* and Pd* obtained by anodically modifying in 0.5 M H₂SO₄ the surface of Ag–Au, Cu–Au, Ag–Pd, and Cu–Pd alloys containing no less than 50 at. % of the noble metal. It is found that a qualitative correlation exists between variations in thermodynamic and electrocatalytic activities of both Au* and Pd* following a change in the surface concentration of vacancies in alloys of constant composition and in the volume concentration of the electronegative component in alloys with approximately identical concentrations of vacancies. Such a correlation may be due to the existence of some factor through which an anodically-modified alloy affects the electrocatalytic process. The factor, presumably the alloy's electronic structure, is more generic than the alloy's volume composition, the nature of components, and the vacancy concentration.